Luminair



A. FROGET Aug, 9, i932.

LUMINAIR Filed Dec. 6, 1928 INVENTOR @MJ/ @afn I mw ATTORNEY Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE ANDR FROGET, 0F PARIS, FRANCE, ASSIGNOR TO HOLOPHANE COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK LUMINAIR Application led December 6, 1928, Serial No. 824,204, and in France December 17, 1927.

The present invention relates to lighting or signalling apparatus and comprises a bowl or plate of prismatic glass, by means of which rays received directly from the light source, as well as those reected by a relector behind the source, are distributed in the desired direction.

One of the principal characteristics of the invention resides in the fact that instead of the lamp being placed in the device with its axis horizontal, as usual, the axis of the lamp is vertical or placed in a-substantially vertical plane, presenting an advantage from the point of view of ventilation. This construction also permits the unobstructed use of the central-portion of the device, so that this portion can be used for greater refraction and emission of beam. Another characteristic consists in the formation of a reflector of prismatic glass with radial prisms in the annular zone and concentric prisms in its central zone thus providing many advantages from the point of view of manufacture, since by this formation Well formed prisms can be traced throughout the central part.

The invention also particularly resides in the combination of the aforesaid prismatic reiector in which the annular zone has a parabolic contour While the central zone has a spherical contour. When these zones are provided with the prisms described above they cooperate to emit from a refracting prismatic plate covering the face of the device a central light flux of parallel rays and an annular iux of rays which are parallel, divergent or diffusing, as desired. This combination can be used for signalling, for lighting house fronts or for advertising signs. The invention has other advantages which will appear in the following description.

Figure l is a vertical sectional view of a luminair;

Figure 2 is an elevational view taken in the direction of the arrow 2 of Figure l showing a form of cover plate;

Figure 3 is an enlarged crosssectional view of the cover plate taken on the line 3-3 of Figures l and 2; and

Figure 4 is a front plan view of the refiector.

The luminair consists of a reliector R, a lamp L having its light center at S, and a prismatic glass cover plate G in the form of a roundel closing the front of the reflector R. The central part of the optical system (reflector and refracting glassware) being free of the lamp support, thus operates on the beam for reflection andrefraction of light without the usual obstruction. The reflector R is preferably prismatic and, in the form shown, is divided into two zones, an annular zone 1" of parabolic contour and provided with radial reflecting prisms 7 and with a central zone r of spherical contour provided with annular concentric reflecting prisms 8, the focus of the annular zone and the center of the central zone being coinci dent with the center of the luminous source S. The new arrangement by which the radial prisms are replaced by annular prisms at the center of the reflector has the following advantages.

Such reiiectors are usually formed with radial prisms which diminish in size from the edge of the reflector toward the center, and in these the prisms at the center are too small in section, and, because they are formed in the bottom of the mold, are too misshapen to function properly. By substituting annular refiecting prisms for these small prisms at the central zone, the prismatic angles can be kept sharp throughout their surfaces and function in the manner for which they are designed.

The reflector R, having an annular zone of the contour described herein, reflects rays coming from the source in a parallel beam, as indicated by ray X, while the central zone reflects back corresponding rays coming from the source, as indicated by the ray Z. The reflector can be used in the apparatus with a prismatic refracting plate (i designed according to the distribution desired.

The drawing shows a form of cover plate G designed for obtaining an elliptical distribution of light. The central zone 9 of the cover plate is provided on its interior with parallel prismatic ribbings 10, symmetrical with respect to the horizontal plane passing through the center of the luminair and designed to mfract divergent rays received di- .rectly from the light source and those relected back by the reflector r to condense the li ht horizontally and permit it to spread sideways. The path of these rays is indicated at Z, Z. Annu ar zone 1l of the cover plate is provided with parallel prisms 12 h aving a rofile somewhat as indicated in Figure 3. hese prisms haveV the effect of spreading l the. parallel rays X received from the parabolic portion r of the reflector, as indicated in Figure 3.

The combination of these two lighting effects allows a uniform distribution to a sur# 15 face normal to the optical axis of the appara'\ tus and elongated in size with reference to Figure 2. It is evident that the refracting cover can be turned at an angle of 90 so as to l make the ribbings 12 horizontal and those of 10 vertical in order to illuminate uniformly 'a surface elongated vertically. It is also evi- -dent that if, 1n place of obtaining the uniform illumination of a surface as described herein, it is desired to obtain other effects, the central rib'bings of 10 need not necessarily be perpendicular to the ribbings 12 of the peripheral zone, but their relative position, as well as their different distributions, can be varied according to the form of beam desired, 3 and can be concentrated or diffused at will.

vThere is considerable divergence of the light raysreceived directly from the light source S by the annular zone, andthis has the advantage that, when the apparatus is turned u through 90 and used for railway signalling, it is visible at points near the signal. Of course, the form given herein is merely illustrative of the invention and it can be varied without departing from the claim made here- I claim: A luminaircomprising a light source, a lass reflector havin a central portion which 1s spherical about te lightsource and pro- 5 vided with totally reflecting concentric risms and an outer annular'portion ofparaolic shape with its focus at the light source and provided with radial reflecting prisms,

and a refracting cover plate having a central v 5 circular rtion opposite the spherical portion of t e refiectorv and adapted to receive the cone of light refiected thereby and the lcone of `direct light and having parallel prisms to refract the divergent rays to conense them in one direction lwithout affecting their spread in directions at right angles thereto, the cover plate also having an annular zone opposite the annular paraboloidal zone ofthe refiector for receiving the parallel '5 rays reflected thereby and direct light, and

being provided with corrugations at right angles to the prisms for spreading such light. lgned at Paris, France, thisv 26th day of November, 1928.`

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